Method for measuring lung function in small animals and mice

The determination of lung function in small animals and mice is mainly achieved through five methods: plethysmography, forced oscillation, non-invasive airway resistance detection, lung compliance testing, and blood gas analysis. These techniques can evaluate airway resistance, lung ventilation function, and gas exchange efficiency, and are suitable for research on respiratory system diseases.

1. Volumetric recording method:

calculates tidal volume and respiratory rate through changes in air pressure inside a closed chamber. During the experiment, mice were placed in a specially designed chamber, and sensors recorded the pressure fluctuations caused by chest movements, which can simultaneously monitor respiratory waveforms. This method can non invasively obtain basic respiratory parameters, but it should be noted that animal stress may affect data accuracy. It is recommended to measure in a quiet environment.

2. Forced oscillation method:

uses multi frequency oscillation waves to evaluate airway resistance and lung elasticity. By inserting a specific frequency oscillation signal into the respiratory tract through endotracheal intubation, the impedance spectrum is obtained by analyzing the relationship between pressure and flow velocity. This technique is sensitive to bronchial constriction models and can distinguish between central and peripheral airway lesions, but requires operation under anesthesia.

3. Non invasive airway detection:

uses a hood type device to measure peak expiratory flow rate and airway resistance. Animals maintain autonomous breathing and record their breathing curves through flow sensors. Suitable for long-term dynamic monitoring, it can reduce anesthesia interference, but has low sensitivity to minor functional changes.

4. Pulmonary compliance test:

Inject quantitative gas through endotracheal intubation and measure the pressure volume curve to evaluate lung tissue elasticity. Using a progressive inflation and deflation protocol, calculate static compliance to reflect alveolar expansion ability. This method is the gold standard for evaluating pulmonary fibrosis, but it requires strict control of operating pressure to avoid lung injury.

5. Blood gas analysis:

Collect arterial blood to detect oxygen partial pressure and carbon dioxide partial pressure. Obtain samples through carotid or ventricular puncture, and evaluate gas exchange efficiency in combination with blood oxygen saturation. This method can directly reflect the final effect of respiratory function, but it is an invasive operation that requires controlling the blood collection volume within 1% of body weight. Before the experiment, animals need to be acclimated to the environment for at least 3 days, maintaining a room temperature of 25 ℃ and a humidity of 40% -60%. Fasting for 4 hours before measurement, but drinking water freely to avoid anesthesia drugs affecting respiratory parameters. It is recommended to choose adult mice weighing 20-30 grams, and specific baseline data should be established for different strains. Pay attention to instrument disinfection during operation, and use silicone tubing for tracheal intubation to reduce mucosal damage. Data analysis should exclude motion artifacts and ensure statistical validity with at least 8-10 samples per group. Long term research can use micro implantable sensors for continuous monitoring, but surgical tolerance needs to be considered. Combining histopathological examination can improve the reliability of the results.